In the field of skin external preparations including cosmetics and skin external drugs, water-absorbing polymers are used in aqueous cosmetics and aqueous skin external drugs as a thickening/gelling agent for stabilizing the system. The water-absorbing polymers, however, have the drawback that they give an unpleasant slimy feel on use. This is because the polymer forms a gel network structure, which is stable and thus difficult to break down on use. Because of the unpleasant feel, sometimes the use of the cosmetic or drug must be interrupted. While it is desired to solve the problem, non-silicone water-absorbing polymers are unsatisfactory. See Patent Document 1.
To solve the drawback of an aqueous skin external preparation using a water-absorbing polymer, Patent Documents 2 and 3 propose water-absorbing polymers having a silicone structure incorporated therein and cosmetic compositions comprising the same. These water-absorbing polymers still have problems including difficult control of three-dimensional structure due to cross linking of epoxy groups, and a change with time of water absorption capability.
Thus, it is desirable to create water absorbing polymers that provide optimal aesthetics as well as to provide other desirable cosmetic properties. If an ingredient used to formulate cosmetic products can multiple functions, this means fewer ingredients can be used in the formulation which reduces cost and the potential for adverse interactions between ingredients.
Particularly in cosmetic applications, it is very desirable to create a film on skin that blurs skin defects such as lines, wrinkles, or minor skin imperfections. In addition to provide aesthetically pleasing thickening properties, when the same polymers provide other benefits such as optically improving the appearance of the skin surface this provides a further advantage.